304 M. BABADOOST
chemical and microbial degradation in the soil, which may enhance
toxicity against soil-borne plant pathogens, includingPythiumspp.
Soil solarization along with suitable organic matter gave better dis-
ease control compared to individual treatments of either soil solar-
ization or organic matter. Satya et al. (2005) reported that composted
chicken manure alone at 5381 kg ha−^1 reduced populations ofPythium
species significantly and when combined with heat (42◦C), eradicated
thePythiumpopulation from the soil. Organic soil amendments can
help protect soil microbial biomass and enzymatic activities from the
detrimental effect of heating caused by soil solarization (Pokharel 2010).
Overall, chemical management of Pythium diseases is difficult (Fol-
man et al. 2004; Parveen and Sharma 2015). The range of effective reg-
istered fungicides available for managing Pythium diseases is limited.
Moreover, resistance developed by pathogens to fungicides has ren-
dered certain fungicides ineffective (Lin et al. 2002). Thus, fungicides
should be used in rotation or mixed with other fungicides with different
modes of actions. Overall, the management ofPythiumspecies should
be with strategies of integrated approaches of non-chemical practices
with fungicides.
Natural plant products have been used for management ofPythium
species. Extracts of a number of plants have been reported to suppress
colony development ofPythiumspecies on culture media, as well as
plant infection (Haouala et al. 2008; Parveen and Sharma 2015). Aque-
ous extracts of numerous plants have been investigated for their effects
onPythiumspecies, which were reviewed and reported by Parveen and
Sharma (2015).
IV. CONCLUDING REMARKS
More than 200 infectious and noninfectious diseases have been reported
on cucurbits. The diseases are caused by bacteria, fungi, oomycetes,
viruses, nematodes, parasitic plants, and environmental conditions.
Oomycete pathogens cause very destructive diseases on cucurbits.
The main oomycete pathogens of cucurbits arePhytophthora capsici,
Pseudoperonospora cubensis,andPythiumspp.Phytophthora capsici
incites of damping-off, crown rot, vine blight, leaf spot, and fruit rot.
Pseudoperonospora cubensiscauses downy mildew.Pythiumspecies
cause seedling damping-off, root rot, and fruit rot.
Phytophthora capsici,P. cubensis,andPythiumspecies can infect
cucurbit plants at all growth stages that may result in 100% crop losses.
These pathogens cause multi-cycle diseases and cycle of each disease
can be completed in a few days. Thus, management of these pathogens